An industrial control system is now used in almost every industrial area such as oil & gas, chemical, pharmaceutical, paper, mining and metal field. One of main purposes of the industrial control system is to control the field devices automatically and run the process fast, efficiently and precisely. Normally, the control system contains engineering stations, operation stations, controllers, I/O stations, terminal boards and field devices.
A digital output signal is widely used in process control for applications like ON/OFF control and relay output. A digital output module outputs high or low level based on the operation or control algorithm.
An advanced digital output module supports multiple output channels and diagnostic and protection functions. Short circuit detection is important diagnostic information which can used to inform the user if there is a cable short circuited in the field. Such short circuit detection is necessary for the digital output module because the short circuit may cause big current in the control loop which may damage the electronic elements in the module.
Standard short circuit detection and protection solution uses a smart high side switch (such as Infineon BTS4141N) to measure an internal temperature and realize current limitation and short circuit protection. However, this kind of switch is relatively expensive. For a digital output module with multiple output channels, using this type of switch for each channel would result in a rather high total cost for the module.